Magnetizable core



J. P. GLASS MAGNETIZABLE CORE March 3, 1964 2 Sheets-Sheet 1 Original Filed May 10 1951 WAC/rm iii V March 3, 1964 J. P. GLASS 3,123,747

MAGNETIZABLE CORE Original Filed May 10, 1951 2 Sheets-Sheet 2 United States Patent O 3,123,747 MAGNETIZABLE CORE John P. Glass, Haverford Township, Delaware County, Pa, assignor to Litton Industries, Inc., Beverly Hills, Califi, a corporation of Delaware Continuation of application Ser. No. 225,515, May 10, 1951. This application Apr. 22, 1960, Ser. No. 24,121 12 Claims. (Cl. 317--158) The present invention relates to magnetizable cores for electro-magnets for producing a magnetic field in a workspace having a relatively low magnetic permeability, and more particularly where the work-space is an air gap, a vacuum gap, a gaseous gap or like interruption in the mag netic flux-path, as, for instance, cores for deflection coils disposed around the space in the neck of cathode-ray tubes (used in television sets, Oscilloscopes, radar equipment and the like) through which the electron-beams projects, or cores for the stators or rotors of motors and synchros, where the work-space is the air gap between stator and rotor of the \air gap between the ends of the teeth of the core. This patent is a continuation of my prior co-pending application Serial No. 225,515, filed May 10, 1951, and now abandoned.

An object of the present invention is to reduce the quantity of the expensive high-magnetic-permeability metal used in such cores without impairing the operation or efiiciency of the coil or unit of which it is a part. A further object is to reduce the weight of the coil or unit of which the coil is a part.

Other objects will appear from the following specification and accompanying drawings.

In the drawings wherein like reference characters indicate like parts,

FIGURE 1 represents an end elevational view of a magnetizable core representing one embodiment of the present invention, with the outer lamination partly broken away.

FIGURE 2 represents a side elevational view of a magnetizable core representing the embodiment shown in FIGURE 1.

FIGURE 3 represents a fragmentary perspective view of two laminations of the embodiment shown in FIG- URE 2; separated somewhat in order better to show their relationship to each other.

FIGURE 4 represents an end elevational view of a magnetizable core representing another embodiment of the present invention, with the outer lamination partly broken away.

FIGURE 5 represents a side elevational View of a magnetizable core representing the embodiment shown in FIGURE 4.

FIGURE 6 represents a fragmentary perspective view of two laminations of the embodiment shown in FIGURE 5; separated somewhat in order better to show their relationship to each other.

FIGURE 7 represents an enlarged fragmentary perspective View of a lamination representing another embodiment of the present invention wherein the lamination has transversely-extending tips at the ends of the teeth thereof.

FIGURE 8 represents a fragmentary cross-sectional view, taken on a plane in which the axis of the core lies, of the lower half of a plurality of laminations of the form ice indicated in FIGURE 7; assembled in the manner shown in FIGURES 1 to 3, inclusive.

FIGURE 9 represents a fragmentary cross-sectional View, taken on a plane in which the axis of the core lies, of the lower half of a plurality of laminations similar to the forms indicated in FIGURES 4 to 6, inclusive, but including the tooth-tip like that shown in FIGURE 7; assembled in the manner shown in FIGURES 4 to 6, inclusive.

FIGURE 10 represents a cross-sectional View, taken on a plane in which the axis of the core lies, of the core of a deflection-coil, embodying the laminations indicated in FIGURE 7.

FIGURE 11 represents an end elevational view of a magnetizable core representing another embodiment of the present invention.

FIGURE 12 represents an enlarged fragmentary perspective view of a lamination of the embodiment shown in FIGURE 11.

FIGURE 13 represents a cross-sectional view taken generally along lines 1313 of FIGURE 11, on an enlarged scale.

In the embodiment of the present invention illustrated in FIGURES 1, 2 and 3, the magnetizable core 15 is adapted for use in a deflection-coil, and is composed of toothed annular laminations 20 of ferromagnetic metal, and like toothed annular laminations 21 of non-magnetic sheet material (such as fiber or the like) alternating with each other; the thickness of the non-magnetic laminations 21 being of the order of /3 to 5 times the thickness of the ferromagnetic laminations 20.

Each of the laminations 2i? and 21 comprises an annulus having radia1ly-extending teeth 17 and intervening coil-slots or winding-slots 13; with a working space 19 between the ends of the teeth 17. The slots 18 and the working space 12 are formed by punching, blanking or otherwise removing the corresponding portions from the sheet of lamination material. The core is then formed by assembling alternate ferromagnetic laminations 2t? and non-magnetic laminations 21, with the teeth 17 and the working space 19 thereof in alignment with each other, as indicated in FIGURES 1, 2 and 3.

Where the flux-path of an electro-magnet is interrupted by an air gap or similar gap of relatively high reluctance constituting its working space, I can eliminate a third or a half (or more) of the total amount of ferromagnetic metal (which would be present in a core of the same axial dimension" if formed entirely of contiguous laminations of ferromagnetic laminations) with an increase in reluctance of only 4% or so. Thus, where a high fluxdensity in the Working space (which constitutes an interruption in the flux-path) is not needed, I reduce the total amount of ferromagnetic material to the number of ferromagnetic laminations which will just accommodate the maximum flux-density required in the working space without saturating such laminations; the rest of the ferromagnetic laminations I omit and replace with nonmagnetic spacing means (between the retained ferromagnetic laminations), with an increase in reluctance of only a few percent as compared with the reluctance of a core of the same overall outside dimensions but formed of a solid stack of contiguous ferromagnetic laminations.

Even the 4% or so of increase in reluctance I may further reduce with substantially the same saving in ferromagnetic laminations and with the same reduction in the Weight of the core (and of the coil or unit of which it is a part), by providing at each end of the core two contiguous ferromagnetic laminations, as, for instance, the pair of outermost ferromagnetic laminations 2d and Zll-a and the pair of outermost ferromagnetic laminations 2i) and 29-h, in FIGURE 2; the inner ferromagnetic lamination 2% (between Zt a and 2b) being regularly spaced apart from each other by the nonmagnetic laminations 21 as in FEGURES l, 2, 3 and 8 or by like air spaces as in the embodiments shown in FIGURES 4 to 6 and 7 to 9.

In FIGURE 10 the outer annular portions of the ferromagnetic laminations are stacked in closely adjacent or contiguous relation to each other while the inwardly extending teeth 17 thereof are spaced apart, with air gaps therebetween, by means of the short bent-over flange-like tooth-tips 26 formed on the inner ends of the teeth 17.

Whether the ferromagnetic laminations are spaced apart from each other by non-magnetic laminations 21 or by means providing air gaps between such laminations, the spacing between the laminations is of the order above indicated.

In either case the spaces between the ferromagnetic laminat-ions constitute a very substantial part of the total overall length of the core and substantially reduces the overall weight of the core and of the coil or unit of which it is a part.

Thus, for instance, with only 50% of the axial dimensional core made up of ferromagnetic laminations (and the other 50% made up of non-magnetic laminations or of air gaps), the reluctance is increased only 4% or so; resulting both in very substantial savings in the cost and in the weight of the coil or electromagnetic unit of which the core is a part.

in the embodiment shown in FIGURES 4 to 6, inclusive, the core 24 is formed of ferromagnetic laminations as having spacing projections, ribs or ridges 25 formed on the annuli thereof. If desired, similar spacing projections, ribs or ridges may also be formed on the teeth 17 of the laminations. The spacing projections, ribs or ridges 25 'on the annulus or annular portion of the lamination 2%, are circumferentially distributed around the annulus. Each spacing projection, rib or ridge 25 is preferably disposed at an angle and in asymmetric relation to the adjacent spacing projection, rib or ridge 25, or such projections may be spaced on the face of a lamination in any other suitable manner so that projections on adjacent laminations will not nest. The spacing projections, ribs or ridges 25 may be provided on one face or on both faces of the laminations If provided only on one face of each lamination, then the height of such spacing projection, rib or ridge (measured at a right angle to the face of the lamination) is equal to the desired spacing between the ferromagnetic laminations; when spacing (as indicated above) may be anywhere from onethird the thickness of the ferromagnetic lamination to five times the'thickness of the ferromagnetic lamination. By providing such spacing projections on both faces of each lamination, facing projections may be abutted against each other, so that the height of each projection need be only one-half of the spacing desired between laminations. V

The geometry of the magnetic path and the overall magnetic properties of the core may also be furtherimproved, for some uses, by forming bent-over flange-like tips 26 on the ends of the teeth 1'7 of the ferromagnetic laminations 24); with the overal laxial dimension of the tip-end 26 being equal to the thickness of the lamination plus the desired spacing between adjacent laminations. The tooth-tips 26 may also be used in the core construction illustrated in FIGURES l to 3,.inclusive, wherein non-magnetic laminations Z1 intervene and effect the spacing between the ferromagnetic laminations 26. In

such case, however, the teethli of the ferromagnetic laminations Eda-re made suiiiciently longer than the teeth 4 of the non-magnetic laminations 21 so that the bent-over tips 26 will extend over the ends of the teeth 17 of the non-magnetic laminations.

Where the bent-over tooth-tips 26 are used in the core structure such as indicated in FIGURES 8 and 9, wherein there is only air between the spaced-apart ferromagnetic laminar-ions, as in FIGURE 9, or wherein there is only air between the teeth 17 of such spaced-apart ferromagnetic laminations, as in FIGURE 8, the bent-over tooth-tips 26 also serve to keep the aligned teeth of adjacent laminations in the desired spaced-apart relation to each.

In either case, however, the bent-over tooth-tips 26 serve to provide a generally axially continuous tooth-end from one end of the core to the other, between adjacent winding-slots 18.

In the embodiment shown in FIGURE 10, the core 27 is composed of the laminations illustrated in FIGURE '7, to form a central working space 19a of a substantially longer axial dimension than the axial dimension of the outer cylindrical surface of the core or of the radially outermost portion of the core. shown in FIGURE 10, a plurality of ferromagnetic laminations 2%, of the embodiment shown in FIGURE 7, are stacked with their teeth 17 and slots 13 in registration or alignment with each other, without any laminations or other spacing means intervening the outer annular portions of such ferromagnetic laminations 2d. The outermost peripheries of the annular portions are then forced together or axially compressed (preferably prior to annealing so as to bring them into contiguous relation to each other, and the outer peripheries of the annular portions are then clamped in the so com ressed condition by means of a retaining ring or sleve 28 whose ends 29-11 and 29-b are then turned inwardly to form inwardly extending flanges 29a and 2%. Such inward turning of the ends of the sleeve to form the flanges 29-a and 29-b may be effected by pressing or spinning or otherwise inwardly forming the ends of the sleeve (after the sleeve has been placed over the compressed outer peripheries of the annular portions of the ferromagnetic laminations).

The bent-over tooth-tips 26 space the teeth 17 from each other in the manner indicated in FIGURE 10 so that the inner axial dimension X of the core 27 will be substantially greater than the outer axial dimension thereof; thus providing a generally elongated working space 19-a (slightly flared at its outer ends) of a length equal to the inner axial dimension X.

This permits the windings 3t to pass around the end laminations 20 without materially increasing the overall axial length of the finished deflection-coil, so that the magneticfield produced by such deflection-coil will be effective along a maximum portion of the electron-beam of the cathode-ray tube 31 between the flared portion 32 thereof and the focusing-coil 33 thereof,

1 may further increase thellux-carrying capacity (or correspondingly decrease the reluctance) of the core, while still spacing the ferromagnetic laminations substantially apart from each other with only air between them, by providing nesting (or non-nesting) flanges along the outer peripheries of the annular portions of the ferromagnetic laminations and along the sides of the teeth 17 thereof ad along the base or innermost portions of the slots 13 thereof, as in the embodiment shown in FIG- URES 11 to 13, inclusive. In this embodiment, each ferromagnetic lamination 34- is,v generally dish-shaped, with its annular or peripheral portion including a web 35 having an outer flange 36, and with similar flanges 37 along the inside of the annular web 35 between the teeth 33, at the roots thereof. The teeth 38 are generally V- shaped, in cross-section with the flange-like sides 39 thereof inclined at any suitable angle to each other (and to V the plane of the web 35) so that when the laminations 38 r are stacked, as indicated in FIGURE 13,; the angle of inclination of the various webs 36, 37 and 39 will effect a spacing between laminations; with the amount of spacing To form the core 27.

depending on the angle of said flanges. Thus, in the embodiment shown in FIGURES 11 to 13, inclusive, less material is punched out or removed from the sheet of ferromagnetic metal to provide the working space and the winding-slots between the teeth, so that for the same cross-section of slots, more ferromagnetic metal is provided Without increasing the number of laminations and without decreasing the space between adjacent ferromag netic laminations. Thus, the projected area of each tooth 3-8 is no greater than the area of the fiat core-tooth 17 in the other embodiments of the present invention, and yet the teeth 38 contain approximately twice the amount of metal contained in the teeth 17. This is achieved without any increase in cost because the pieces of metal punched out of sheet-metal stock is only scrap metal.

Hence, in the embodiment shown in FIGURES 11 to 13, inclusive, the amount of effective or usable ferromagnetic metal in each lamination is increased without increasing the radial or circumferential dimension of the coil (or of each lamination) and without reducing the area of the slots 18 between the teeth 38 and without increasing the cost of the core. Nor does this embodiment increase the total number of spaced apart laminations required or reduce the spacings therebetween, but may indeed permit the reduction of the total number of laminations required and an increase of the spacings therebetween.

Having described my invention, I claim the following:

1. A generally annular laminated magnetizable core structure having ferromagnetic laminations which define a working space separate and distinct from the core, portions of adjacent laminations adjacent said working space being substantially spaced from each other, and portions of said laminations not adjacent said working space being generally contiguous to each other, whereby said core structure adjacent said working space is substantially longer than the portion of said core structure not adjacent said working space.

2. A generally annular ferromagnetic lamination for use in a laminated magnetizable core structure, comprising a lamination having an outer annular portion and circumferentially spaced-apart pole-teeth extending inwardly therefrom with the inner ends thereof defining a working space and having spacer-projections formed integrab 1y with said lamination and pressed outwardly from at least one face thereof, said projections being so arranged that a plurality of such laminations may be stacked with spaces intervening the laminations maintained by said projections.

3. A generally annular ferromagnetic lamination for use in a laminated magnetizable core structure, comprising a lamination having an outer annular portion and circumferentially spaced-apart pole-teeth extending inwardly therefrom with the inner ends thereof defining a working space and having an integral projection extending transversely from a surface of said lamination a distance equal at at least one-third /3) and not substantially more than the thickness of said lamination, said projection being a flange extending from the end portion of each tooth at 90 degrees, whereby when arranged in a stack the core structure adjacent said working space is substantially longer than the portion of said core structure not adjacent said working space.

4. A generally annular ferromagnetic lamination for use in a laminated magnetizable core structure, comprising a lamination having an outer annular portion and circumferentially spaced-apart pole-teeth extending inwardly therefrom with the inner ends thereof defining a working space and having a plurality of projections asymmetrically disposed in relation to each other and formed integrally with said lamination and pressed outwardly therefrom in a direction transverse to the major dimension of the lamination, said projections being constructed and arranged whereby a plurality of such laminations may be stacked and spaced apart from each other without nesting.

5. A generally annular laminated magnetizable core structure comprising stacked ferromagnetic laminations having an outer annular portion and circumferentially spaced-apart pole-teeth extending inwardly therefrom with the inner ends thereof defining a Working space and having spacer-projections formed integrally therewith and pressed outwardly from at least one face thereof, said spacer-projections being so arranged that said ferromagnetic laminations are spaced apart from each other thereby.

6. A generally annular laminated magnetizable core structure comprising stacked ferromagnetic laminations having inwardly extending pole-teeth and winding-slots therebetween and defining a working space separate and distinct from said core, spacers between adjacent ferromagnetic laminations spacing them apart from each other and providing substantial air spaces between adjacent laminations throughout a major portion of the proj cted areas thereof.

7. A generally annular laminated magnetizable core structure comprising stacked ferromagnetic laminations having inwardly extending pole-teeth and winding-slots therebetween and defining a working space separate and distinct from said core, spacers between each pair of adjacent ferromagnetic laminations spacing them apart from each other at distances of the order of at least one-third and not substantially more than the thickness of the ferromagnetic laminations and providing corresponding air spaces between adjacent laminations throughout a major portion of the projected area thereof.

8. A generally annular laminated magnetizable core structure comprising stacked ferromagnetic laminations having an outer annular portion and circumferentially spaced-apart pole-teeth extending inwardly therefrom with the inner ends thereof defining a working space and having a plurality of spacer projections asymmetrically disposed in relation to each other and formed integrally therewith and pressed outwardly therefrom in a direction transverse to the major dimension of the laminations, said projections being constructed and arranged to space said laminations apart from each other in such stack without nesting.

9. A generally annular laminated magnetizable core structure comprising stacked ferromagnetic laminations including an outer peripheral web, a plurality of inwardly extending pole-teeth formed integrally with said web, surfaces of said pole-teeth disposed at an angle to the surface of said Web forming projections in the direction transverse to the major dimension of the laminations, and air gaps formed by said angular surfaces spacing the teeth of each lamination from the teeth of adjacent laminations.

10. A generally annular laminated magnetizable core structure comprising stacked ferromagnetic laminations including an outer peripheral web and a plurality of inwardly extending pole-teeth formed integrally with said web, surfaces of said pole-teeth disposed at an angle to the surface of said Web forming projections in the direction transverse to the major dimension of the lamina tions, and air gaps formed by said projections spacing the teeth of each lamination from the teeth of adjacent laminations.

11. A generally annular laminated magnetizable core structure comprising ferromagnetic laminations having inwardly extending pole-teeth and winding-slots therebetween and defining a working space separate and distinct from the core, adjacent ferromagnetic laminations being spaced from each other at distances of the order of at least one-third and not substantially more than the thickness of the ferromagnetic lamination, and the spaces between said laminations being air gaps.

12. A generally annular laminated magnetizable core structure including ferromagnetic laminations having a plurality of pole portions whose ends face each other and References Cited in the file of this patent UNITED STATES PATENTS 635,739 Berginann Oct. 31, 1899 8 Geisenhoner Feb. 6, 1900 McElroy Sept. 25, 1966 Apple June 6, 1933 Richards et a1 Oct. 23, 1941 Sigmund et a1. June 17, 1947 Morrison Ian. 3, 1950 FOREIGN PATENTS Great Britain Aug. 10, 1949 

1. A GENERALLY ANANULAR LAMINATED MAGNETIZABLE CORE STRUCTURE HAVING FERROMAGNETIC LAMINATIONS WHICH DEFINE A WORKING SPACE SEPARATE AND DISTINCT FROM THE CORE, PORTIONS OF ADJACENT LAMINATIONS ADJACENT SAID WORKING SPACE BEING SUBSTANTIALLY SPACED FROM EACH OTHER, AND PORTIONS OF SAID LAMINATIONS NOT ADJACENT SAID WORKING SPACE BEING GENERALLY CONTIGUOUS TO EACH OTHER, WHEREBY SID CORE STRUCTURE ADJACENT SAID WORKING SPACE IS SUBSTAN- 